Food habits of the two-line eelpout (Bothrocara brunneum: Zoarcidae) at two deep-sea sites in the eastern North Pacific,

Description

Two-line eelpouts were collected from two deep-sea sites in the eastern North Pacific in order to study food habits. The diet of this species is low in diversity, consisting primarily of shrimp-like crustaceans and secondarily of small zoarcid fishes. Although significant differences in diet exist between the two study sites, it appears that two-line eelpouts have a narrow dietary breadth. Previous and concurrent surveys of the region indicate that there is a wide range of potential prey available to two-line eelpouts; however, the species appears to be using a narrow range of benthopelagic fauna, suggesting that it is capable of some degree of prey specialization., Cited By (since 1996):7, CODEN: DRORE, ,

In recent years, concerns have increased regarding accumulation of persistent, lipophilic contaminants by marine mammals. We quantified blood levels of the two most prevalent organochlorine (OC) contaminants of the marine ecosystem in a model species, the harbor seal (Phoca vitulina) from three north-central California populations and a population in Bristol Bay, Alaska. Intensive sampling (n = 190) produced robust quantification of blood concentrations of selected PCBs and DDE, and allowed us to investigate factors affecting levels of these contaminants in seal populations with distinct environments and exposure histories. In the Alaskan samples, PCB and DDE levels were most strongly related to sex and age; OCs increased with age in males and decreased with age in females, likely due to cumulative exposure in males and load-dumping during lactation in females. Among females, an inverse relationship was observed between condition and PCB blood levels. In contrast, in the California seals, in which loads were generally much greater, pups had greater levels of PCBs and DDE than subadults and adults, suggesting stable to decreasing environmental contaminant levels. Spatial heterogeneity and seasonal differences also contributed substantially to variation among harbor seals in contaminant loads. These findings underscore the importance of accounting for demographic, geographic, seasonal, and physiological effects in toxicological studies of marine mammals., Cited By (since 1996):1, ,

We have developed a computer-aided system (Bony Parts) to analyze periodic bands in fish otoliths (or other structures) for age estimation. The image analysis program first scans the image of a thin otolith section, perpendicular to the bands specified by the user. Adjacent scans are averaged and filtered with Fourier transformation or spatial domain convolution. Bands of higher density are detected and are marked and summed on the screen. We evaluated this new technique using subsamples of thin-sectioned otoliths from the bank rockfish Sebastes rufus. The time and effort for cleaning, preparation, sectioning, and mounting are the same for both traditional and computer-aided techniques. The computer-aided technique reduced the time and tedium of counting bands, yet still allowed the user to interactively make subjective decisions about aging criteria. Both approaches produced similar readings, but computer-aided estimates were more precise than traditional readings and required less analysis time. Thus, this new technique allows sample size and precision to be increased for a given amount of effort. Use of this new technique to age 1,897 sections produced von Bertalanffy growth equations that indicate female bank rockfish grow to a larger theoretical maximum size than males (L1 = 500.7 mm versus 438.1 mm total length) but grow at a slightly slower rate (K = 0.054 for females versus 0.073 for males., Cited By (since 1996):11,
Fish and Fisheries, CODEN: TAFSA, ,

The relationship between water motion and living rhodolith beds in the southwestern Gulf of California, Mexico,

Description

Free living, nodular aggregates of non-geniculate coralline algae (rhodoliths) have occurred since the Cenozoic in diverse marine environments around the world. Fossil rhodolith morphology and distribution have been widely used as paleoecological indicators, particularly of water motion. However, few studies have verified these relationships in living beds. The relationship between water motion and rhodolith movement was examined in three subtidal rhodolith beds off the southwestern coast of the Gulf of California, one dominated by wave action and two dominated by tidal currents. Field experiments and simultaneous video and current measurements taken during winter 1996 showed that rhodoliths in the shallow margins (4.5 m depths) of wave-dominated beds moved frequently due to threshold-level velocities from wind-propagated waves. Rhodoliths did not move in the middle and at deep margins of the bed due to attenuation of wave energy. Historical wind records and waveforcasting analysis indicate that shallow rhodolith movement is frequent only in the winter. In deep tidally dominated beds, maximum yearly tidal currents were not sufficient to move rhodoliths. Video and SCUBA surveys showed that bioturbation is an important mechanism for rhodolith movement in all beds. Rhodoliths in 12-m-deep tidally dominated beds and in the deep margins of wave-dominated beds appear to move only occasionally due to bioturbation and severe storms. Results imply that rhodolith morphology and distribution are dependent on a combination of factors. These factors, especially bioturbation, should be considered when using rhodoliths as paleoecological indicators., Cited By (since 1996):66, ,

A new species of Malthopsis (Lophiiformes: Ogcocephalidae) from the western Atlantic Ocean,

Description

A new species of Malthopsis is described from the western Atlantic Ocean, the first Malthopsis known from anywhere outside the Indo-western Pacific region except for Hawaii. Of 25 depth records, all were 275-475 m except one, which was 91 m., Cited By (since 1996):4, CODEN: BMRSA, , , Fish and Fisheries

Analysis of stomach contents for Dasyatis chrysonota revealed that diet varied with size and habitat. The diet of all size classes in the surf zone was comprised primarily of Callianassa spp., Donax spp. and unidentified polychaete species. The medium and large size classes fed primarily on Donax spp., whereas the very large size class fed mainly on Callianassa spp. Polychaetes were of secondary importance as prey for the medium size class. The diet of D. chiysonota in the nearshore zone consisted mainly of Balanoglossus capensis and Callianassa spp. Balanoglossus capensis decreased from an index of relative importance (IRI) of 75.3% for the medium size class to 59.9% for the very large size class, whereas Callianassa spp. increased from 22.8% to 39.4% between the medium and the very large size classes. The offshore zone was the only area in which small size class D. chrysonota were caught. The diet of these small D. chrysonota was primarily polychaetes and amphipods. Polychaetes increased in importance in the medium size class, but declined in each successively larger size class. Conversely, Pterygosquilla armata capensis became the single most important prey item for the very large size class, comprising an IRI of 50.9%. The behaviour pattern used by D. chrysonota to locate and extract prey is described., Cited By (since 1996):27, Fish and Fisheries, CODEN: AJMFA, ,

The European green crab Carcinus maenas is one of the world's most successful aquatic invaders, having established populations on every continent with temperate shores. Here we describe patterns of genetic diversity across both the native and introduced ranges of C. maenas and its sister species, C. aestuarii, including all known non-native populations. The global data set includes sequences from the mitochondrial cytochrome c oxidase subunit I gene, as well as multilocus genotype data from nine polymorphic nuclear microsatellite loci. Combined phylogeographic and population genetic analyses clarify the global colonization history of C. maenas, providing evidence of multiple invasions to Atlantic North America and South Africa, secondary invasions to the northeastern Pacific, Tasmania, and Argentina, and a strong likelihood of C. maenas x C. aestuarii hybrids in South Africa and Japan. Successful C. maenas invasions vary broadly in the degree to which they retain genetic diversity, although populations with the least variation typically derive from secondary invasions or from introductions that occurred more than 100 years ago., Cited By (since 1996):54, CODEN: MOECE, ,

The effects of suspended sediments on the composition of wall communities in Alaskan fjords were investigated by quantitative assessment of underwater photo-quadrats. In fjords with actively retreating tidewater glaciers, suspended sediment levels were extremely high at the heads and were exponentially lower at the mouths. Fjords without glaciers had low suspended sediment levels throughout. The per cent cover and number of species were lowest where sedimentation was highest, at the heads of glacial fjords. Here the wall communities were dominated by a sparse cover of small serpulid worms. Richer communities comprising mostly algae, sponges, hydroids, bryozoans, tunicates and brachiopods were found in fjords without glaciers, and at the mouths of glacial fjords. There was a positive correlation between water clarity and community composition along a gradient from heads to the mouths of fjords with high suspended sediment levels., Cited By (since 1996):3, Invertebrates,
Ecology, CODEN: POBID, ,

Improvement of the pre-deployment net closure procedure used with opening/closing plankton nets,

Description

The construction of a closing device to be used during the deployment of phyto-zooplankton nets utilizing General Oceanics-type opening/closing mechanisms is described. This device (the cowl) decreases system set-up time, decreases contamination from ambient particles while waiting for deployment, protects the net from mechanical tears during descent, and increases system reliability., Cited By (since 1996):2, CODEN: JPLRD, ,